The present invention relates to trial frame devices for eyeglasses and, more particularly, to trial frame systems for simulating multifocal eyeglass prescriptions.
In the course of an eye examination, it is common for a prescriptioner to demonstrate a number of different lens powers and styles to the patient. This frequently is accomplished by the use of a trial frame, such as that disclosed in Cogez U.S. Pat. No. 4,448,501. Such a trial frame is capable of closely replicating the desired eyeglass prescription. However, the device disclosed in the aforementioned patent is only capable of simulating the prescription of single focus eyeglasses; it is not capable of simulating a multifocal eyeglass prescription.
Since a large number of the eyeglass-wearing public requires multifocal lens prescriptions, there is a need to provide a trial frame system which simulates a multifocal eyeglass prescription. Several attempts have been made to provide such a trial frame system, and are disclosed in Hill U.S. Pat. No. 955,333; Cowan U.S. Pat. No. 980,070; Griffin U.S. Pat. No. 1,002,580 and Williams U.S. Pat. No. 2,835,161.
Today, there are large numbers of different multifocal eyeglass styles and lens shapes, including the graduated (no line), executive, flat top, trifocal, round, curve top and above-and-below styles. Of course, each of those styles may be prescribed in a variety of magnifications and sizes to address the growing need for lenses specifically suited to an occupation or activity. Accordingly, a disadvantage common to all of the aforementioned multifocal trial frame systems is that it is not possible to mount the more modern multifocal lens designs due to the lens mounting mechanisms employed, which only allow for stacking of single vision lenses. Further, none of the systems disclosed in the aforementioned patents are capable of accurately simulating the look and feel of a particular multifocal eyeglass prescription.
Accordingly, there is a need for a multifocal trial frame system which is sufficiently flexible to approximate a wide range of multifocal eyeglass prescriptions, and which is capable of providing the subject with a realistic look and feel of a particular multifocal eyeglass prescription.